FIELD OF THE INVENTION
The invention concerns a printing press with a vibrator-like or ductor-like inking unit that includes a vibrator or ductor roller that is movable by a motor via a rotatable cam disc, and a method for operating such a printing press.
The published German Patent Document DE 44 36 102 A1 describes a device and a method for controlled transfer of printing ink. The device includes an ink vibrator or ductor roller reciprocatingly movable by a swivel mechanism having an intermittent drive. In one embodiment of the device, a rotatable motor is provided that is connected to a cam-disc segment having two different radii, however, no information is presented about the type of construction of the motor.
In the published German Patent Document DE 44 28 403 C2, a ductor or vibrator drive is described having a cam disc to which a speed-controllable, irregularly drivable drive is assigned. Also provided is a roller of a supporting lever of the ductor or vibrator roller, the supporting-lever roller running along the cam disc. The cam disc occasionally runs at a speed correlating with the printing speed of the printing press and, when the supporting-lever roller runs along the section of the cam disc that causes the ductor roller to be thrown on and thrown off, the cam disc runs at a constant speed independently of the printing speed.
The last-mentioned patent document does not address either the problems associated with the roller lifting from the cam disc due to centrifugal force, or a reduction in the speed of the cam disc.
In the published European Patent Document EP 0 623 468 B1, a ductor or vibrator inking unit for a printing press is described which includes two cam discs having a large radius of curvature for most of the peripheral contour thereof, and a small radius of curvature in the remaining part of the peripheral contour thereof.
Both the device for the controlled transfer of printing ink and also the ductor inking unit, respectively, represent a favorable structural concept for the basic task of the inking unit and the device, respectively. For other cases, however, these systems are unfavorable. In particular, a cam roller following the described cams can lift from the cam at high machine speeds, the position of the ductor roller being occasionally undefined.